CN112290898B - Frequency reduction sampling and control circuit applied to envelope tracking power supply modulator - Google Patents
Frequency reduction sampling and control circuit applied to envelope tracking power supply modulator Download PDFInfo
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- CN112290898B CN112290898B CN202010969397.0A CN202010969397A CN112290898B CN 112290898 B CN112290898 B CN 112290898B CN 202010969397 A CN202010969397 A CN 202010969397A CN 112290898 B CN112290898 B CN 112290898B
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
- H03F3/21—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers with semiconductor devices only
- H03F3/217—Class D power amplifiers; Switching amplifiers
- H03F3/2171—Class D power amplifiers; Switching amplifiers with field-effect devices
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
- G01R1/30—Structural combination of electric measuring instruments with basic electronic circuits, e.g. with amplifier
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
- H03F1/26—Modifications of amplifiers to reduce influence of noise generated by amplifying elements
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
- H03F3/21—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers with semiconductor devices only
- H03F3/211—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers with semiconductor devices only using a combination of several amplifiers
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
- H03F3/21—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers with semiconductor devices only
- H03F3/213—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers with semiconductor devices only in integrated circuits
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/68—Combinations of amplifiers, e.g. multi-channel amplifiers for stereophonics
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K5/00—Manipulating of pulses not covered by one of the other main groups of this subclass
- H03K5/22—Circuits having more than one input and one output for comparing pulses or pulse trains with each other according to input signal characteristics, e.g. slope, integral
- H03K5/24—Circuits having more than one input and one output for comparing pulses or pulse trains with each other according to input signal characteristics, e.g. slope, integral the characteristic being amplitude
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0003—Details of control, feedback or regulation circuits
Abstract
The invention belongs to the technical field of integrated circuits, and particularly relates to a frequency reduction sampling and control circuit applied to an envelope tracking power supply modulator. The frequency-reduction sampling and control circuit comprises a sampling unit, a filtering unit and a comparison unit, wherein the current control signal DUTY is obtained by sampling, low-pass filtering and comparing the output current of a linear amplifier in the envelope tracking power supply modulator, and the power switch of the switching amplifier is controlled by using the DUTY, so that the tracking speed of the switching amplifier on average power can be ensured while high-frequency components in the envelope signal are effectively filtered, and the efficiency of the envelope tracking power supply modulator is improved.
Description
Technical Field
The invention belongs to the technical field of integrated circuits, and particularly relates to a frequency-reduction sampling and control circuit applied to an envelope tracking power supply modulator.
Background
Signal modulation techniques in modern wireless communication systems are becoming more and more complex in order to achieve high-speed data transmission, with the attendant significant problem of the larger and larger peak-to-average power ratio of the transmitted signal. Signals are transmitted through a power amplifier, and high peak-to-average power ratio signals pose a serious challenge to the efficiency of the power amplifier. The traditional power amplifier is powered by a power supply with a fixed voltage, and the efficiency of the power amplifier is lower when the peak-to-average power ratio of a signal is higher. The envelope tracking power supply modulator can dynamically adjust the power supply voltage of the power amplifier according to the envelope track change of the signal, so that the energy loss is reduced, and the efficiency of the power amplifier is improved.
An envelope tracking power modulator typically comprises a linear amplifier and a switching amplifier. The linear amplifier has the characteristics of large bandwidth and low efficiency, and the switching amplifier has the characteristics of low bandwidth and high efficiency. The combination of the switching amplifier and the linear amplifier provides the low frequency component and the high frequency component of the output envelope power supply, so that the envelope tracking power supply modulator has high speed and high efficiency.
The switching amplifier consists of two parts, namely a power stage and a control stage. The power stage typically includes a power switch and an inductor to convert energy in the form of a switching power supply. The control stage typically includes one or more control signals, one of which is related to the output current of the linear amplifier. The current control signal is obtained by obtaining an output current of the linear amplifier through a current sampling circuit, comparing the output current with a reference value, and if the output current is greater than the reference value, the current control signal is at a high level (or low level), and if the output current is less than the reference value, the current control signal is at a low level (or high level).
The switching frequency of the switching amplifier is closely related to the current control signal. One of the factors affecting the efficiency of a switching amplifier is the switching loss, which is proportional to the switching frequency, so that the switching loss of a switching amplifier is larger for larger switching frequencies. In order to control the switching frequency within a reasonable range, the current control signal needs to be controlled to reduce the frequency of the current control signal. The conventional control method reduces the frequency of the current control signal by increasing the sampling resistance of the output current of the linear amplifier, reducing the hysteresis voltage of a hysteresis comparator in the control stage of the switching amplifier, increasing the power inductance of the control stage of the switching amplifier, and the like. These methods cannot obtain a pure low-frequency control signal, and the high-frequency components always exist in the switching control signal to a greater or lesser extent, which not only increases the switching loss, but also causes electromagnetic interference to the transmitted signal because the frequency falls into the band.
Disclosure of Invention
The invention aims to provide a frequency-reduction sampling and control circuit with a tracking speed of a switching amplifier, which is applied to an envelope tracking power supply modulator.
The invention provides a frequency reduction sampling and control circuit applied to an envelope tracking power supply modulator, which structurally comprises: the device comprises a sampling unit, a filtering unit and a comparing unit; wherein:
the sampling unit includes: a sampling resistor for isolating the output of the linear amplifier from the output of the envelope tracking power modulator;
the sampling unit further includes: a mirror NMOS transistor, a mirror PMOS transistor;
the length of the mirror image NMOS transistor is equal to that of the NMOS power transistor of the output stage of the linear amplifier in the envelope tracking power supply modulator, and the width ratio is 1: n, the grids of the two are connected together, and the drains of the two are connected together; the length of the mirror image PMOS transistor is equal to that of the linear amplifier output stage PMOS power transistor in the envelope tracking power supply modulator, and the width ratio is 1: n, the grids of the two are connected together, and the drains of the two are connected together; the value of N is 200 or a similar order of magnitude; the source of the mirror NNOS transistor is connected with the source of the mirror PMOS transistor;
one end of the sampling resistor is connected with the source electrode of the mirror image NNOS transistor, and the other end of the sampling resistor is connected with the output end of a linear amplifier in the envelope tracking power supply modulator.
Optionally, in the present invention, the sampling unit further includes: a mirror NMOS transistor, a mirror PMOS transistor, a divider resistor and an operational transconductance amplifier;
the lengths of the mirror image NMOS transistor and the NMOS power transistor of the output stage of the linear amplifier in the envelope tracking power supply modulator are equal, and the width ratio is 1: n, the grids of the two are connected together, and the drains of the two are connected together; the length of the mirror image PMOS transistor is equal to that of the linear amplifier output stage PMOS power transistor in the envelope tracking power supply modulator, and the width ratio is 1: n, the grids of the two are connected together, and the drains of the two are connected together; the value of N is 200-1000 (recommended value is 200, generally not more than 1000); the source of the mirror NNOS transistor is connected with the source of the mirror PMOS transistor;
one end of the sampling resistor is connected with the source electrode of the mirror image NNOS transistor, and the other end of the sampling resistor is connected with the output end of a linear amplifier in the envelope tracking power supply modulator;
the non-inverting input end of the operational transconductance amplifier is connected with the output end of the linear amplifier, the inverting input end of the operational transconductance amplifier is connected with the source electrode of the mirror NMOS transistor, and the output end of the operational transconductance amplifier is connected with one end of the sampling resistor;
one end of the divider resistor is connected with the sampling resistor, and the other end of the divider resistor is connected with the source electrode of the mirror NMOS transistor;
the two filtering units are the same; the input ends of the two filtering units are connected with the two ends of the sampling resistor, and the output ends of the two filtering units are connected with the comparison unit.
Optionally, each filtering unit includes a first filtering resistor, and the first filtering capacitor forms a first-order RC filter.
Optionally, each filtering unit includes a first filtering resistor, a first filtering capacitor, a second filtering resistor, and a second filtering capacitor, which form a second-order RC filter.
Optionally, each filtering unit includes a first filtering resistor, a first filtering capacitor, a second filtering resistor, a second filtering capacitor, a third filtering resistor, and a third filtering capacitor, so as to form a third-order RC filter.
Optionally, each filtering unit includes a first filtering resistor, a first filtering capacitor, a second filtering resistor, a second filtering capacitor, a third filtering resistor, a third filtering capacitor, a fourth filtering resistor, and a fourth filtering capacitor, so as to form a fourth-order RC filter.
In the present invention, the comparing unit includes: a hysteresis comparator;
optionally, the hysteresis voltage of the hysteresis comparator is a fixed value;
optionally, the hysteresis voltage of the hysteresis comparator is adjustable.
In the invention, the output current of the linear amplifier is sampled and converted into a sampling voltage value by the sampling unit; filtering high-frequency components in the sampled voltage value through the filtering unit; and comparing the sampling voltage value with the hysteresis voltage of the hysteresis comparator through the comparison unit, wherein the output voltage of the hysteresis comparator is the low-frequency current control signal. The invention thoroughly filters out high-frequency components in the current control signal, reduces the frequency of the current control signal and improves the efficiency of the envelope tracking power supply modulator. Meanwhile, the switching amplifier can be ensured to track the change of the output power of the envelope tracking power supply modulator at a reasonable speed.
Drawings
Fig. 1 is a flow chart of signal processing according to an embodiment of the present invention.
Fig. 2 is a schematic circuit diagram of a sampling unit according to an embodiment of the present invention.
Fig. 3 is a schematic circuit diagram of another sampling unit according to an embodiment of the present invention.
Fig. 4 is a schematic circuit diagram of another sampling unit according to an embodiment of the present invention.
Fig. 5 is a schematic circuit diagram of a filtering unit according to an embodiment of the present invention.
Fig. 6 is a schematic circuit diagram of another filtering unit according to an embodiment of the present invention.
Fig. 7 is a circuit diagram of another filtering unit according to an embodiment of the present invention.
Fig. 8 is a circuit diagram of another filtering unit according to an embodiment of the present invention.
Fig. 9 is a schematic circuit diagram of a comparison unit according to an embodiment of the present invention.
Fig. 10 is a circuit diagram of another comparing unit according to an embodiment of the present invention.
Fig. 11 is a schematic diagram of an application in an envelope tracking power modulator according to an embodiment of the present invention.
Fig. 12 is a schematic diagram of another application in an envelope tracking power modulator according to an embodiment of the present invention.
Fig. 13 is a schematic diagram of another application in an envelope tracking power modulator according to an embodiment of the present invention.
Fig. 14 is a schematic diagram of another application in an envelope tracking power modulator according to an embodiment of the present invention.
Fig. 15 is a schematic diagram of another application in an envelope tracking power modulator according to an embodiment of the present invention.
Reference numbers in the figures: 1 is a linear amplifier, 11, 12, 13 are sampling units, 14, 15 are nodes, 16 is an operational transconductance amplifier, 2 is a load, 211, 212, 221, 222, 231, 232, 241, 242 are filtering modules, 3, 5, 6, 7, 8 are switching amplifiers, and 4 is a control circuit.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the drawings of the embodiments of the present invention. It should be apparent that the described embodiments are only some of the embodiments of the present invention, and not all of them. And the embodiments and features of the embodiments may be combined with each other without conflict. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention without any inventive step, are within the scope of protection of the invention.
Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. The use of "first," "second," and similar terms in the present application do not denote any order, quantity, or importance, but rather the terms are used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items. Unless expressly stated or limited otherwise, the terms "connected," "coupled," and the like are to be construed broadly and encompass, for example, electrical connections and communications; may be directly connected or indirectly connected through an intermediate. It should be noted that the sizes and shapes of the figures in the drawings are not to be considered true scale, but are merely intended to schematically illustrate the present invention. And the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.
First, the design idea and the related signals of the design of the present invention are explained, and referring to fig. 1, the whole circuit is divided into three units, which are a sampling unit, a filtering unit, and a comparing unit. The sampling object of the sampling unit is the output current of a linear amplifier in the envelope tracking power supply modulator, the sampled current is wholly or partially or copied according to a certain proportion and then flows to a sampling resistor Rsen, and a voltage drop is generated on the sampling resistor Rsen. The voltage drop across Rsen is the difference between Vout and Voutc. The filter unit performs low-pass filtering on the waveforms of Vout and Voutc, after the filtering, vout becomes Vout, and Voutc becomes Vocf. The comparison unit compares Vof with Vocf and includes a hysteresis comparator, and the output signal, denoted DUTY, is a frequency-varying square wave, which can be used to control the power switches of the switching amplifier in the envelope tracking power modulator.
An alternative embodiment of the sampling unit in this example is shown in fig. 2. The module 1 is a linear amplifier, and the VIP and VIN are respectively a non-inverting input end and an inverting input end of the module; the module 11 is a sampling unit and comprises a sampling resistor Rsen; module 2 represents other circuitry, typically a load. The output power tubes of the linear amplifier 1 are MP1 and MN1, in the low-voltage process, the MP1 and the MN1 are often separated by using an isolation MOS tube, and in the application, the technology can be used, the isolation MOS tube close to the MP1 can be calculated into the source-drain resistance of the MP1, and the isolation MOS tube close to the MN1 can be calculated into the source-drain resistance of the MN 1. The linear amplifier 1 provides current to the load, which flows from Vout out of the linear amplifier, through Rsen and into the load. The voltage drop across Rsen is the difference between Voutc and Vout, which is proportional to the output current of the linear amplifier 1.
An alternative embodiment of the sampling unit in this example is shown in fig. 3. The module 12 is a sampling unit, the lengths of the mirror NMOS transistors MN2 and MN1 are equal, and the width ratio is 1: n, the grids of the two are connected together, and the drains of the two are connected together; the mirror PMOS transistors MP2 and MP1 have the same length, and the width ratio is 1: n, the grids of the two are connected together, and the drains of the two are connected together; the value of N is of the order of 200 or more. In a low-voltage process, the MP1 and the MN1 are often separated by using an isolation MOS transistor, and in this application, the isolation MOS transistor close to the MP1 can be counted as a source-drain resistance of the MP1, and the isolation MOS transistor close to the MN1 can be counted as a source-drain resistance of the MN1, so that in the sampling unit 12, the isolation MOS transistor copied in the same proportion should also be added. The output current of the linear amplifier 1 can flow from the node Vout to the load, and the current of the mirror transistor flows from Voutc through the sampling resistor Rsen to the load, which is approximately proportional to the output current of the linear amplifier 1, the ratio being about 1 n, so that the voltage drop across the sampling resistor Rsen is proportional to the output current of the linear amplifier 1.
An alternative embodiment of the sampling unit in this example is shown in fig. 4. Module 13 is the sampling unit, and mirror image NMOS transistor MN2 is equal with MN 1's length, and the width ratio is 1: n, the grids of the two are connected together, and the drains of the two are connected together; the lengths of the mirror PMOS transistors MP2 and MP1 are equal, and the width ratio is 1: n, the grids of the two are connected together, and the drains of the two are connected together; the value of N is on the order of 200 or more. In a low-voltage process, the MP1 and the MN1 are often separated by using an isolation MOS transistor, and in this application, the isolation MOS transistor close to the MP1 can be counted as a source-drain resistance of the MP1, and the isolation MOS transistor close to the MN1 can be counted as a source-drain resistance of the MN1, so that in the sampling unit 13, the isolation MOS transistor copied in the same proportion should also be added. The output current of the linear amplifier 1 flows from the node 15 to the load, the output current of the mirror MOS transistor flows from the node 14 to the resistor Rvd, and the operational transconductance amplifier 16 can make the voltages of the node 15 and the node 14 the same or similar through negative feedback, so as to ensure that the ratio of the current flowing from the mirror transistor to the output current of the linear amplifier is 1. The output current of the mirror transistor flows through the resistor Rvd and the sampling resistor Rsen, and then enters the operational transconductance amplifier 16, and a voltage drop is formed across the sampling resistor Rsen, and the voltages at the two ends of the sampling resistor Rsen are Vout and Voutc, respectively. The resistance value and the resistance value ratio of the resistance Rvd and the sampling resistance Rsen can be adjusted, and the amplitude of voltage change at two ends of the sampling resistance Rsen can be adjusted.
An alternative embodiment of the filter unit in this example is shown with reference to fig. 5. The filtering module 211 performs low-pass filtering on the input signal Vout and outputs Vof; the filtering module 212 performs low-pass filtering on the input signal Voutc to output Vocf; the filtering module 211 is identical to the filtering module 212, and both are first-order low-pass filters formed by a resistor and a capacitor.
An alternative embodiment of the filter unit in this example is shown in fig. 6. The filtering module 221 performs low-pass filtering on the input signal Vout and outputs Vof; the filtering module 222 performs low-pass filtering on the input signal Voutc, and outputs Vocf; the filtering module 221 is identical to the filtering module 222, and both are second-order low-pass filters formed by two resistors and two capacitors.
An alternative embodiment of the filter unit in this example is shown in fig. 7. The filtering module 231 performs low-pass filtering on the input signal Vout and outputs Vof; the filtering module 232 performs low-pass filtering on the input signal Voutc to output Vocf; the filtering module 231 is identical to the filtering module 232, and is a third-order low-pass filter composed of three resistors and three capacitors.
An alternative embodiment of the filter unit in this example is shown in fig. 8. The filtering module 241 performs low-pass filtering on the input signal Vout and outputs Vof; the filtering module 242 performs low-pass filtering on the input signal Voutc to output Vocf; the filtering module 241 is identical to the filtering module 242, and is a fourth-order low-pass filter composed of four resistors and four capacitors.
An alternative embodiment of the comparison unit of this example, shown in figure 9, comprises a comparator. Vip is the non-inverting input of the comparator, vin is the inverting input of the comparator, vout is the output of the comparator, and the output signals DUTY, vof, and Vocf are fed to the input of the comparator. Since the DUTY signal is used in different ways in different envelope tracking power modulators, it is not strictly specified which input terminals Vof and Vocf are specifically fed to, and the positions of Vof and Vocf may be selected when the DUTY signal is inverted with respect to the desired logic, e.g. Vof is connected to Vip, vocf is connected to Vin, vof is connected to Vip, or an inverter may be connected to the comparator output. The comparator is a hysteresis comparator, fig. 9 also shows the relationship between the output voltage and the input voltage of the comparator, where Vin is a fixed voltage, when the Vip voltage is greater than Vin + VH, the output Vout is at a high level, and when the Vip voltage is less than Vin-VH, the output Vout is at a low level, where VH is the hysteresis voltage of the hysteresis comparator, which is an inherent parameter of the circuit, and is suggested to be designed to be several milli-hundred volts.
An alternative embodiment of the comparison unit of this example, shown with reference to fig. 10, comprises a comparator. Vip is the non-inverting input of the comparator, vin is the inverting input of the comparator, vout is the output of the comparator, and the output signal is DUTY; the control signal Sc is a voltage or current signal and is used for controlling the hysteresis voltage of the comparator; vof and Vocf are fed to the input of the comparator. Since the DUTY signal is used in different ways in different envelope tracking power modulators, it is not strictly specified at which input terminals Vof and Vocf are fed in, and the positions of Vof and Vocf can be selected to be swapped when the DUTY signal is opposite to the desired logic, e.g. Vof is connected to Vip, vocf is connected to Vin, vof is connected to Vip, or an inverter is connected to the comparator output. Fig. 9 also shows the output voltage of the comparator used in relation to the input voltage, where the hysteresis voltage V (Sc) is a function of the control signal Sc. For example, vin is a fixed voltage, when the Vip voltage is greater than Vin + V (Sc), the output Vout is high, and when the Vip voltage is less than Vin-V (Sc), the output Vout is low, and the control signal Sc can flexibly adjust the magnitude of the hysteresis voltage.
The invention effectively controls the frequency of the DUTY through low-pass filtering, and thoroughly removes high-frequency components in the DUTY. However, when the output power of the envelope tracking power supply modulator changes, the average power of the change is also consumed by the low-pass filtering, and if the cut-off frequency of the filter is too low, the speed of DUTY tracking average power change is also slow, which is disadvantageous in terms of efficiency. In order to ensure the tracking speed of the average power while ensuring the effective filtering of the high frequency component in the envelope signal, a low-pass filtered signal | Vof-Vocf | is required, and the peak-to-peak value of the high frequency component is less than about 2 times of the hysteresis voltage of the comparator in the comparison unit. The technician can flexibly design the parameters of the circuit according to the rule.
An alternative application of the present embodiment in an envelope tracking power modulator is shown in fig. 11. The linear amplifier 1 and the switching amplifier 3 together supply a current to the load supplying radio frequency power amplifier PA. The switching amplifier 3 consists of a frequency reduction sampling and control circuit 4 and a power level circuit; the power stage circuit generally comprises a power transistor, two non-overlapping circuits and a driving circuit of the power transistor; the down-sampling and control circuit 4 consists of a comparison unit, a filtering unit and a sampling unit, and each unit can be realized by any optional embodiment; the down-sampling and control circuit 4 directly controls the power stage circuit.
An alternative application of the present embodiment in an envelope tracking power modulator is shown in fig. 12. The linear amplifier 1 and the switching amplifier 5 together provide a current for the load providing radio frequency power amplifier PA. The switching amplifier 5 consists of a frequency reduction sampling and control circuit 4, other control level circuits and a power level circuit; the power stage circuit generally comprises a power transistor, two non-overlapping circuits and a driving circuit of the power transistor; other control circuits are other control logics designed by designers according to performance requirements; the frequency-reducing sampling and control circuit 4 consists of a comparison unit, a filtering unit and a sampling unit, and each unit can be realized by any optional embodiment; and the other control stage circuits are combined with the DUTY signal and other designer-defined signals to jointly control the power stage circuits.
An alternative application of the present embodiment in an envelope tracking power modulator is shown in fig. 13. The linear amplifier 1 and the switching amplifier 6 together supply current to the load from the radio frequency power amplifier PA and the capacitor Cc isolates the output of the linear amplifier from the load so that the linear amplifier only needs to supply part of the ac component of the output current. The switching amplifier 6 consists of the frequency reduction sampling and control circuit 4 and a power level circuit; the power stage circuit generally comprises a power transistor, two non-overlapping circuits and a driving circuit of the power transistor; the frequency-reducing sampling and control circuit 4 consists of a comparison unit, a filtering unit and a sampling unit, and each unit can be realized by any optional embodiment; the down-sampling and control circuit 4 directly controls the power stage circuit.
An alternative application of the present embodiment in an envelope tracking power modulator is shown in fig. 14. The linear amplifier 1 and the switching amplifier 7 together supply the current to the load from the radio frequency power amplifier PA and the capacitor Cc isolates the output of the linear amplifier from the load so that the linear amplifier only needs to supply part of the ac component of the output current. The switching amplifier 7 consists of the frequency reduction sampling and control circuit 4, other control level circuits and a power level circuit; the power stage circuit generally comprises a power transistor, two non-overlapping circuits and a driving circuit of the power transistor; other control circuits are other control logics designed by designers according to performance requirements; the frequency-reducing sampling and control circuit 4 consists of a comparison unit, a filtering unit and a sampling unit, and each unit can be realized by any optional embodiment; and the other control stage circuits are combined with the DUTY signal and other designer-defined signals to jointly control the power stage circuits.
An alternative application of the present embodiment in an envelope tracking power modulator is shown in fig. 15. The linear amplifier 1 and the switching amplifier 8 together supply the current to the load from the radio frequency power amplifier PA and the capacitor Cc isolates the output of the linear amplifier from the load so that the linear amplifier only needs to supply part of the ac component of the output current. The switching amplifier 8 consists of the frequency-reduction sampling and control circuit 4, other control level circuits and a power level circuit; the power stage circuit generally comprises a power transistor, two non-overlapping circuits and a driving circuit of the power transistor; other control circuits are other control logics designed by designers according to performance requirements; the frequency-reducing sampling and control circuit 4 consists of a comparison unit, a filtering unit and a sampling unit, and each unit can be realized by any optional embodiment; and the other control stage circuits are combined with the DUTY signal and other designer-defined signals to jointly control the power stage circuits.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (3)
1. A down-sampling and control circuit for use in an envelope tracking power modulator, comprising: the device comprises a sampling unit, a filtering unit and a comparing unit; wherein:
the sampling unit includes: a sampling resistor, a mirror NMOS transistor and a mirror PMOS transistor;
the sampling resistor is used for isolating the output end of the linear amplifier from the output end of the envelope tracking power supply modulator;
the length of the mirror image NMOS transistor is equal to that of the NMOS power transistor of the output stage of the linear amplifier in the envelope tracking power supply modulator, and the width ratio is 1: n, the grids of the two are connected together, and the drains of the two are connected together; the length of the mirror image PMOS transistor is equal to that of the linear amplifier output stage PMOS power transistor in the envelope tracking power supply modulator, and the width ratio is 1: n, the grids of the two are connected together, and the drains of the two are connected together; the value of N is 200-1000; the source of the mirror NNOS transistor is connected with the source of the mirror PMOS transistor;
one end of the sampling resistor is connected with a source electrode of the mirror image NNOS transistor, and the other end of the sampling resistor is connected with an output end of a linear amplifier in the envelope tracking power supply modulator;
the two filtering units are the same; the input ends of the two filtering units are connected with the two ends of the sampling resistor, and the output ends of the two filtering units are connected with the comparison unit;
the sampling unit further includes: a voltage dividing resistor, an operational transconductance amplifier;
the non-inverting input end of the operational transconductance amplifier is connected with the output end of a linear amplifier in the envelope tracking power supply modulator, the inverting input end of the operational transconductance amplifier is connected with the source electrode of the mirror NMOS transistor, and the output end of the operational transconductance amplifier is connected with one end of the sampling resistor;
one end of the divider resistor is connected with the sampling resistor, and the other end of the divider resistor is connected with the source electrode of the mirror NMOS transistor;
each filtering unit is a first-order, second-order, third-order or fourth-order RC low-pass filter; each order of RC low-pass filter consists of a filter resistor and a filter capacitor;
in order to guarantee the tracking speed of the average power while guaranteeing that the high frequency component in the envelope signal is effectively filtered, the absolute value of the difference of the output signals after being filtered by two low-pass filters is required, and the peak-to-peak value of the high frequency component is less than 2 times of the hysteresis voltage of a comparator in a comparison unit.
2. The downsampling and control circuit of claim 1, wherein the comparison unit comprises a hysteresis comparator; the hysteresis voltage of the hysteresis comparator is a fixed value.
3. The downsampling and control circuit of claim 1, wherein the comparison unit comprises a hysteresis comparator; the hysteresis voltage of the hysteresis comparator is adjustable.
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